The present invention relates to a so-called nanoimprint lithography apparatus which transfers a pattern formed on a mold to an object such as a resin material by bringing the mold into contact with the object.
A so-called nanoimprint lithography technique has been proposed for manufacturing various devices having fine patterns including semiconductor chips such as ICs and LSIs, display devices such as liquid crystal panels, detecting devices such as magnetic heads, image-pickup devices such as CCDs, and MEMS (Micro Electro-Mechanical Systems)
The nanoimprint lithography involves pushing a mold (also referred to as an original plate or a template) having a fine pattern formed thereon onto a wafer coated with a resin material (a resist) to transfer the pattern to the resist. (see S. Y. Chou, et al., Science, vol. 272, p. 85-87, 5 Apr. 1996).
Propositions of the nanoimprint lithography include a transfer method in which polymer used as a resist is heated to a glass transition temperature or higher to increase the fluidity to facilitate the flow of the resist at the time of transfer (a heat cycle method), and a transfer method in which an ultraviolet-curing resin (a UV-curing resin) is used as a resist and is irradiated with light while it is in contact with a transparent mold to achieve curing (called a photo-curing method or a UV-curing method). The photo-curing method is often used in manufacturing the semiconductor device.
FIGS. 15(1) to 15(3) show a transfer process in the photo-curing method.
A first step (1) is a stamping step. A mold M made of a material (for example, quartz) which passes ultraviolet light is pushed onto a resist UVR made of UV-curing resin coating a substrate (a wafer) W. This causes the UV-curing resin to flow along a pattern formed on the mold.
A second step (2) is a curing step. With the mold M pushed onto the resist UVR on the substrate W, ultraviolet light UV is applied thereto. As a result, the resist is cured in the same shape as the pattern on the mold M.
A third step (3) is a mold release step. The mold M is released from the cured resist UVR. After the mold release, the resist UVR having the shape of the pattern is left on the substrate W. In this manner, the pattern is transferred to the substrate.
In manufacturing the semiconductor device, the abovementioned transfer process is generally repeated on a single substrate to transfer a plurality of patterns all over the substrate.
RIE processing is performed to remove the base of the transferred resin (resist) pattern. The resulting pattern is equivalent to a resist pattern provided by transfer in a conventional photolithography apparatus. The subsequent steps are the same as those in a conventional LSI manufacturing process.
The stamping step and the curing step can be performed faster by speeding up the mechanical operation and applying illumination light with higher illuminance, respectively. However, the mold release step is not easily performed quicker simply by speeding up the mechanical operation since the fine pattern may be damaged by the friction between the mold and the cured resist. To address this, the mold is subjected to mold release coating to improve the mold release property (see U.S. Pat. No. 6,309,580).
The resist, however, is not always convenient for the mold release depending on the conditions of device manufacturing. Specifically, even when typical mold release coating is performed on the mold, the mold release property cannot be improved sufficiently in some types of resists.